Answer
f(x) is even
Work Step by Step
In f(x), all the terms in the polynomial have powers of x as multiples of 2.
Hence, f(x)=f(-x), for replacing x with -x in the polynomial will result in exactly the same terms as $x^{2k}=(-x)^{2k}$ for k =2,4,....,2n (k is even).
Hence the function is even.
